Refining of animal and vegetable oils



Oct. 28, 1941. B. H. THURMAN REFIIICIA OF ANIMAL AND VEGETABLE OILSFiled Aug. 31, 1938 l lil Patented Oct. 28, 1941 Benjamin n. Thurman,nronxvme, N. y., assignor to Refining, Inc., Reno, Nev., a corporationof Nevada Application August31, 1938, Serial No. 227,826

' (or. 26o-42s) 9 Claims.

This invention relates to a process of refining animal and vegetableoils, and more particularly to a continuous process in which the freefatty acids are removed from the oils by solvents.

An object of the present invention is to provide an improved process ofrefining animal and vegetable oils in which a. solvent for thefree fattyacids of the oilis employed.

Another object of the invention is to provide a continuous process ofrefining animal and vegetable oils in which a solvent for the free fattyacids of the oil is admixed with the unrened oil and the solvent phasecentrifugally separated from the oil phase.

A further object of the invention is to provide a continuous process ofsolvent refining animal and vegetable oils in which the process iscarried on in a closed system out of contact with the air.

Ay still further object of the invention is to provide a continuousprocess of solvent refining vegetable oils in which high temperaturesare employed for effecting a thoroughA admixture of the oil with thesolvent.

Other objects and advantages of the invention Will appear in thefollowing description of preferred embodiments thereof, given inconnection with the attached drawing, which is a schematic diagram of anapparatus capable of carrying outthe process.

Referring more particularly to the drawing: III indicates a supply tankfor the oil tov be refined; II indicates a closed supply tank for afatty acid solvent; I2 indicates a proportioning mechanism for `the oiland solvent; I3 indicates a mixing'device for the oil and solvent; I4indicates a centrifugal separator for separating the solvent phase fromthe oil phase, and I5 and I8 indicate respectively vapor separatingchambers for separating solvent from the fatty acids and the refinedoil.

In accordance with the present invention, oil to be refined is withdrawnfrom the tank I0 by a proportioning pump I1 forming' part of theproportioning mechanism I2 and forced through a heating device I8 shownas a coil I9 positioned in a casing 20 through which any desired heatingmedium may be circulated. Solvent is withdrawn vfrom tank II by aproportioning pump 2I and forced through a heating device 22 which maybe similar to theheating device I8. The proportioning pumps Il and 2lmay be driven by a variable speed electricmotor 23 with a speed changedevice 24 positioned between the pumps -to deliver the combined streamof oil `and sol,

heat exchange device 21 which oil and solvent may be withdrawn from thetanks I0 and Il. The proportioning device disclosed is shown merely wayof example, and any suitable type of proportioning device capable ofdelivering accurately proportioned streams of oil and solvent may besubstituted therefor.

The oil and solvent from the heating devices I8 and 22 respectively aredelivered to a ow mixing device 25, In certain operations in-accordancewith the present invention, merely bringing the oil and solvent togetherin ilow is suicient, but in other operations it is desirable vent to themixer I3 indicated as a mechanical agitator, capable of thoroughlymixing substantially immiscibley liquids. Inoperations not involving theuse of the mixer I3, the oil and solvent mixture can be bypassed aroundthe mixer I3 by a pipe 26. In either case, the mixture of oil andsolvent is preferably passed vthrough a may be similar to the heatingdevice I8, for bringing the mixture to the correct temperature forseparation. The mixture is then delivered to the continuous centrifugalseparator I4 which is of theclosedtypel to prevent escape of solvent.The solvent phase containing the free fatty acids of the oil isdischarged from the separator I4 as the lighter eiliuent through a pipe28 and delivered into a storage tank 29-from which it may be withdrawnas a stream by means of a pump 30 and passed through a heating device 3|into the vapor separating chamber I6. 'Ihe oil,fwhich is substantiallyfree of fatty acids and solvent, is discharged from the separator I4 asthe heavy eiiluent through a pipe 32 into a storage4 tank 33, from whichit may be withdrawn as a stream by means of aL pump 34 and passedthrough a heating device 35 into the vapor separating chamber I6. Thesolvent vapors are separated from the fatty acids and refined oilsrespectively in the vapor separating chambers I5 and I6 and delivered toa condenser 36 wherein the solvent so that any desired proportions andamounts 'of 55 is condensed to liquid form and delivered to a receiver3l, Condensed solvent maybe returned by means of a pump 38 to thesolvent tank II for re-use in the process.

If, under the temperature conditions in the evaporating chambers I5 andI6, a vacuum is necessary to substantially completelyvaporize thesolvent from the fatty acids and the refined oil, a vacuum may bemaintained in the condenser and evaporating system by means of a vacuumpump 39 connected to the receiver 31 through pipes 40 and 4I. In manyinstances a vacuumis found unnecessary, in which case the receiver 3T'may bev vented to the solvent tank II through the pipe 4I and pipe 42lby opening the valve 43 invpipe 4I and closing the valve 44 in pipe 40.The 'storage tanks 29 and 33 are employed toA compensate for any slightvariations in ow between the steps of the process, and may be relativelysmall in size so as to provide for substantially continuous flow of thematerials through the process. These tanks maybe vented back to thesolvent tank II by means of pipes 45, 46 and 42. Substantially solventfree fatty acids may be withdrawn from the vapor separating chamber I5by means of a pump 41, and refined oil substantially free of solvent andfatty acids may be withdrawn from the vapor separating chamber I6 bymeans of a pump 48.

In carrying out the process of the present invention, the preferredsolvent is isopropyl alcohol. Howeven'other alcohols, particularly theto approximately 20%, preferably between 5 and under pressure untillcooled prior to centrifugal separation.

Since the oil and solvent phases become less miscible as the temperatureis lowered, it is desirable to cool the mixture in the heat exchangedevice 21 to the lowest temperature practical for the production ofliquid, easily ilowable eiiluents from the centrifugal I4. Thisstatement applies to either the relatively low temperature or the hightemperature mixing step. Since the oils and fatty acids vary widely intheir viscosity characteristics, depending upon the saturation 20%`water, are extremely miscible with fatty If mixing is carried on at'relatively low tempera.

tures, for example between 70 and 120HF., it is usually necessary to,employ a high speed mechanical agitator such as the mixer I3 in orderto substantially completely dissolve the fatty acids in the solvent. Thetemperature of mixing necessary for complete solution of the fatty acidsin the solventv will depend upon the amount of fatty acids in the oiland the amount o f solvent employed, but

will ordinarily be between`the temperatures mentioned if intensemechanical agitation is employed. The amount of solvent employed variesinversely as the amount of free fatty acids in the oil. That is to say,the greater the amount of free fatty acids. the less the amount ofsolvent that is required to secure a separable solventfatty acid phase.Since the amount of free fatty acids in animal and vegetable oils variesbetween extremely wide limits, it is impossible to give a precisepercentage of solvent applicable to all oil. In general the amount ofsolvent employed will range between 5 and 200%, based on the weight ofthe oil.

vAn alternative wayl of securing an intimate mixture between the oil andsolvent is to bring the temperature of mixing to a relatively hightemperature, for example, approximately 200 F., at which temperaturesubstantial portions of the oil are soluble in the alcohol solvent.'I'hese temperatures may be obtained by either heating the oil orsolvent in the heating devices I8 and 22, respectively,'or heating boththe oil and solvent in these heating devices. This heating step ispreferablycarried onunderl pressure to prevent vaporiz'ation of thelsolvent, which pressure may be obtained by the proportioning pumps I1and 2| and restricting the discharge from the flow mixer 25. Themechanical agitator I3 is rendered unnecessary by high temperaturemixing, such that the mixture may be maintained thereof, and also thefluidityf of the fatty acid solvent phase varies with the amount ofsolvent employed, no precise temperature applicable to every oil can begiven. In general, the best temperature for separation will vary4 fromconsiderably below room temperature up to F., but satisfactoryseparation can ordinarily be accomplished in the neighborhood of 70 to80 F.

The fatty acid phase is preferably heated in the heating device 3I to atemperature sulcient to cause.separation in vapor form of substantiallyall of the solvent from the fatty acids in the vapor .separating chamberI5. The solvent is relatively easily vaporized from the fatty acids andthev temperature necessary for such vaporization varies from slightlybelow. the boiling point of the solvent if a vacuum is employed tosomewhat above the boiling point of the particular solvent employed ifno vacuum is maintained in the vapor separating chamber. It is preferredto heat the mixture of solvent and fatty acids in the heating device 3lto substantially above' the boiling point of the solvent at the pressurein the heating device so that substantial vaporization of solvent isproduced in the heating device. This enables sufllcient heat to beimparted to the mixture that no additional heat is necessary in thevapor separating chamber I5, although additional heat may be supplied tcthe vapor separating chamber I5 by means of a suitable heating jacket(not shown). The oil from which the solvent fatty acid phase has beenseparated by the centrifugal separator I4, usually contains a smallamount of entrained solvent. This solvent may be separated from the oilby heating in the heating device 35 and vapor separation in the vaporseparating chamber I6 in substantially the same manner as separation ofthe solvent from the fatty acids.

It will be noted that the portions of the system in which solvent ispresent 'are entirely closed from the atmosphere, so that loss ofsolvent is substantially prevented. This is true since the fatty acidsand refined oil removed from the system contain substantially nosolvent. Since the alcohol will also precipitate the minor constituentssuch as gums and some coloring matter, these materials are also removedfrom the oil. Thus a refined oil is produced which is substantially freeof` fatty acids and minor constituents such as phosphatidea'proteins,resins, and carbohydrates. These materials are separated with the fattyacids and may be easily removed therefrom by subsequent treating stepssuch as precipitating thenr from the fatty acids with 1 water, boricacid solutions or neutral slightly alkaline or slightly acid solutionsof salts, which do not react with the fatty acids. This precipitatedmaterial can be settled or continuously centrifugally-separated from thefattyacids to" leave substantially pure fatty acids. Although therefined oil is substantially free of fatty acids and the minorconstituents referred to, in many cases it contains considerablecoloring matter which maybe subsequently removed by any of thedecolorizing steps known to the art. The treatment with solvent andvaporization steps, however, will substantially deodorize the oil thatis produced.

One of the chief difdculties in solvent refining of vegetable oils hasbeen the formation of a difficulty separable emulsion between thesolvent, the water contained therein and the oil, as the minorconstituents of the oil are excellent emulsifying agents. -It has beenfound that lengthy contact between the solvent and the oil, particularlyif mechanical agitation is employed, favors the formation of suchemulsion. In the present process the oil and solvent may be admixedrapidly and the mixture promptly thereafter separated in order toprevent the formation of such an emulsion. Thus, the time of contactbetween the oil and solvent may sometimes be as short las one to twolminutes, and need never exceed ten to fifteen minutes. It will be seenthat I have disclosed a continuous and rapid process of solvent refiningvegetable and` animal oils in which the solvent is maintained in aclosed system and is continually re-used in the process. Also, refinedoil substantially free of fatty acids is `produced and high qualityfatty acids are recovered'.

While I have disclosed the preferred embodiments of my invention, it isunderstood that the details thereof may be varied within the scope ofthe following claims.

I claim:

1. The process of refining vegetable oils containing free fatty acids,which comprises, mixing in a closed system a stream of said oil with astream of a solvent which is miscible with said free fatty acids butsubstantially immiscible with said oil, thereby forming a concurrentstream containing a mixture of an oil phase and a solvent-fatty acidphase, continuously centrifugally separating said oil phase from saidsolvent-fatty acid phase, and vaporizing the solvent from saidsolvent-fatty acid phase for re-use in said process.

2. The continuous process of refining animal and vegetable oilscontaining free fatty acids, which comprises, admixing in a closedsystem a stream of said oil with a stream of solvent comprising a loweraliphatic alcohol containing water thereby forming a concurrent streamcontaining a mixture of an oil phase and a solventfatty acid phase,performing said mixing at a relatively low temperature whereby saidsolvent dissolves said fatty acids but does not substanf tially dissolveoil, to form an oil phase and a solvent phase and continuouslycentrifugally .separating said oil phase from said solvent phase toproduce an oil substantially free of free fatty acids. y

3. The process of refining animal and vegetable oils containing' freefatty acids, which comprises, admixing a stream of said oil in a closedsystem with a lower aliphatic alcohol containing water, performing saidmixing at an elevated temperature whereby said alcohol dissolves saidfree fatty acids and a substantial portion of said oil, cooling theresulting mixture to render said oil substantially miscible in saidalcohol and form an oil phase and a solvent phase, thereafter deliveringa concurrent stream containing said oil phase and said solvent phase toa continuous centrifugal separator and continuously centrifugallyseparating said oil phase from said solvent phase so as to producerefined voil substantially free of free fatty acids,

4. The process of refining animal and vegetable oils containing freefatty acids, which comprises, continuously mixing said oil with asolventwhich dissolves said free fatty acids but does not substantiallydissolve said oil to form a resulting' concurrent stream containing anoil phase and a solvent phase. delivering said stream to a centrifugalseparator, and continuously centrifugally separating said oil phase fromsaid solvent phase to produce a refined oil substantially free of freefatty acids.

5. The continuous process of refining animal and vegetable oilscontaining free fatty acids, which comprises, admixing a stream of saidoil with a stream of solvent comprising a lower aliphatic alcoholcontaining water, performing said mixing at a' relatively lowtemperature whereby said solvent dissolves said fatty acids but does notsubstantially dissolve oil, to form a resulting concurrent streamcontaining an oil phase and a solvent phase, delivering said resultingstream to a centrifugal separator, continuously centrifugally separatingsaid oil phase from said solvent phase to produce an oil substantiallylfree ofv free fatty acids, and vaporizing said solvent from saidsolvent phase, condensing said solvent and admixing the same withadditional oil in said process.

6. The process of refining animal and vegetable oils containing freefatty acids, which comprises, continuously mixing said oil with asolvent which dissolves said free fatty acids but does not substantiallydissolve said oil to form a resulting vconcurrent stream containing anoil phase and a solvent phase, delivering said stream to a centrifugalseparator, continuously centrifugally separating said oil phase fromsaid solvent phase to produce a 'refined oil substantially free of freefatty acids, andl vaporizing said solvent from said solvent phase,condensing said solvent and admixing the same with additional oil insaid process.

7. The process of refining animal and vegetable oils containing freefatty acids, which comprises,

mixing with said oil a solvent for said fatty acids which is misciblewith said oil at an elevated temperature but immiscible therewith at alower temperature', performing said mixing at said elevated temperaturesov as to substantially -completely dissolve said fatty acids in saidsolvent, cooling the resulting mixture to form an oil phase and asolvent phase containing said fatty acids, thereafter delivering aconcurrent stream containing said oil phase and said solvent phase to acontinuous centrifugal separator and centrifugally separating saidsolvent phase from said oil phase to produce an oil substantially freefrom free fatty acids.

8. The process of refining animal and vegetable oils containing` freefatty acids, which comprises,

' mixing with said oil a solvent for said fatty acids which ismisciblewith said oil at an elevated temperature but immiscibletherewith at a lower temperature, performing said mixing at saidelevated temperature so as to substantially completely dissolve saidfatty acidsf'in said solvent, cooling the resulting mixture to form anoil phase and a solvent phase containing said fatty acids, thereafterdelivering a concurrent stream containing said oil phase and saidsolvent phase to a separating zone and separating said solvent phasefrom said oil phase by difference in specific free fatty acids.

- 9. The process of rening animal and vegetable oils containing freefatty acids, which comprises,

concurrent stream containing an oil phase and a solvent phase,delivering said concurren stream to a separating zone and separatingsaid oil phase from said 'solvent phase to produce a recontinuouslymixing said oil with a solvent which 6 fined oil substantially free offree fatty acids.

dissolves said free fatty acids but does not substantially dissolve saidoil to form a resulting BENJAMIN H. THURMAN.

